package com.shixihub.ssh;

/**
 * @author LiShixi 2021/7/2 4:55 下午
 */
/* -*-mode:java; c-basic-offset:2; indent-tabs-mode:nil -*- */
/**
 * This program will demonstrate SSH through jump hosts.
 * Suppose that you don't have direct accesses to host2 and host3.
 *   $ CLASSPATH=.:../build javac JumpHosts.java
 *   $ CLASSPATH=.:../build java JumpHosts usr1@host1 usr2@host2 usr3@host3
 * You will be asked passwords for those destinations,
 * and if everything works fine, you will get file lists of your home-directory
 * at host3.
 *
 */

import com.jcraft.jsch.*;

import javax.swing.*;
import java.awt.*;

public class JumpHost {
    public static void main(String[] arg){

        try{
            JSch jsch = new JSch();

            if(arg.length <= 1){
                System.out.println("This program expects more arguments.");
                System.exit(-1);
            }

            Session session = null;
            Session[] sessions = new Session[arg.length];

            String host = arg[0];
            String user = host.substring(0, host.indexOf('@'));
            host = host.substring(host.indexOf('@')+1);

            sessions[0] = session = jsch.getSession(user, host, 22);
            session.setUserInfo(new MyUserInfo());
            session.connect();
            System.out.println("The session has been established to "+user+"@"+host);

            for(int i = 1; i < arg.length; i++){
                host = arg[i];
                user = host.substring(0, host.indexOf('@'));
                host = host.substring(host.indexOf('@')+1);

                int assinged_port = session.setPortForwardingL(0, host, 22);
                System.out.println("portforwarding: "+
                        "localhost:"+assinged_port+" -> "+host+":"+22);
                sessions[i] = session =
                        jsch.getSession(user, "127.0.0.1", assinged_port);

                session.setUserInfo(new MyUserInfo());
                session.setHostKeyAlias(host);
                session.connect();
                System.out.println("The session has been established to "+
                        user+"@"+host);
            }

            ChannelSftp sftp = (ChannelSftp)session.openChannel("sftp");

            sftp.connect();
            sftp.ls(".",
                    new ChannelSftp.LsEntrySelector() {
                        public int select(ChannelSftp.LsEntry le) {
                            System.out.println(le);
                            return ChannelSftp.LsEntrySelector.CONTINUE;
                        }
                    });
            sftp.disconnect();

            for(int i = sessions.length-1; i >= 0; i--){
                sessions[i].disconnect();
            }
        }
        catch(Exception e){
            System.out.println(e);
        }
    }

    public static class MyUserInfo implements UserInfo, UIKeyboardInteractive{
        public String getPassword(){ return passwd; }
        public boolean promptYesNo(String str){
            Object[] options={ "yes", "no" };
            int foo=JOptionPane.showOptionDialog(null,
                    str,
                    "Warning",
                    JOptionPane.DEFAULT_OPTION,
                    JOptionPane.WARNING_MESSAGE,
                    null, options, options[0]);
            return foo==0;
        }

        String passwd;
        JTextField passwordField=(JTextField)new JPasswordField(20);

        public String getPassphrase(){ return null; }
        public boolean promptPassphrase(String message){ return true; }
        public boolean promptPassword(String message){
            Object[] ob={passwordField};
            int result=
                    JOptionPane.showConfirmDialog(null, ob, message,
                            JOptionPane.OK_CANCEL_OPTION);
            if(result==JOptionPane.OK_OPTION){
                passwd=passwordField.getText();
                return true;
            }
            else{ return false; }
        }
        public void showMessage(String message){
            JOptionPane.showMessageDialog(null, message);
        }
        final GridBagConstraints gbc =
                new GridBagConstraints(0,0,1,1,1,1,
                        GridBagConstraints.NORTHWEST,
                        GridBagConstraints.NONE,
                        new Insets(0,0,0,0),0,0);
        private Container panel;
        public String[] promptKeyboardInteractive(String destination,
                                                  String name,
                                                  String instruction,
                                                  String[] prompt,
                                                  boolean[] echo){
            panel = new JPanel();
            panel.setLayout(new GridBagLayout());

            gbc.weightx = 1.0;
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            gbc.gridx = 0;
            panel.add(new JLabel(instruction), gbc);
            gbc.gridy++;

            gbc.gridwidth = GridBagConstraints.RELATIVE;

            JTextField[] texts=new JTextField[prompt.length];
            for(int i=0; i<prompt.length; i++){
                gbc.fill = GridBagConstraints.NONE;
                gbc.gridx = 0;
                gbc.weightx = 1;
                panel.add(new JLabel(prompt[i]),gbc);

                gbc.gridx = 1;
                gbc.fill = GridBagConstraints.HORIZONTAL;
                gbc.weighty = 1;
                if(echo[i]){
                    texts[i]=new JTextField(20);
                }
                else{
                    texts[i]=new JPasswordField(20);
                }
                panel.add(texts[i], gbc);
                gbc.gridy++;
            }

            if(JOptionPane.showConfirmDialog(null, panel,
                    destination+": "+name,
                    JOptionPane.OK_CANCEL_OPTION,
                    JOptionPane.QUESTION_MESSAGE)
                    ==JOptionPane.OK_OPTION){
                String[] response=new String[prompt.length];
                for(int i=0; i<prompt.length; i++){
                    response[i]=texts[i].getText();
                }
                return response;
            }
            else{
                return null;  // cancel
            }
        }
    }
}
